The basic operations on customization variables are to set and retrieve their values. New variables can also be added.
The customization variables also valid in the main program out of the HTML converter are handled differently if they are strings or arrays. Conversely, customization variables only relevant for the conversion phase set in the main program are always set like string variables, in particular by associating array or hash references to customization variables.
This section describes customization variables set in the main program. These variables are in general passed to converters. It is also possible to set customization variables in the converters only, not in the main program. This is explained later on (see Setting and Getting Conversion Customization Variables).